A steam strainer is a component within a quick-closing valve in turbomachines. A quick-closing valve allows abrupt interruption of a pipe flow. The steam strainer serves to protect the quick-closing valve, especially the moving parts and those that follow from foreign bodies which are carried with the flow and which can lead to breakdown of the quick-closing valve or to damage to subsequent plant parts, such as the blades.
In a common embodiment, the steam strainer has a sleeve-like shape with a cylindrical or conical lateral surface, the strainer surface, which is flowed through from the outside inward. A disadvantage of using steam strainers is the increase in flow resistance of the relevant steam passage and the high pressure losses in the flow. In particular, simple wound strainers and hole strainers produce very high pressure losses which have a negative effect on the power of the steam turbine.
DE 375 304 C discloses a steam strainer in which a strainer body which is produced by winding mutually adjacent wires onto a filter drum.
DE 102009007240 A1 discloses a steam strainer with a corrugated strainer surface.
However, steam strainers are subjected to the loads prevailing in a steam turbine, for example the vibratory loads or the temperature variations. These can destroy the steam strainer after a relatively short service time.
The suitability of the steam strainer for repairs is very limited. If the flowed-through surface is clogged by foreign particles, or if the lateral surface is damaged, it is usually necessary to exchange the entire steam strainer. In addition, it is substantially more difficult to produce a lateral surface with an optimized through-flow surface using conventional production technologies, for example turning, milling, boring or welding. This is however very cost-intensive.